Mullite-containing carrier for ethylene oxide catalysts

Abstract

The present invention relates to an improved carrier for an ethylene epoxidation catalyst, the carrier comprising alumina in combination with a stability-enhancing amount of mullite. The invention is also directed to an improved catalyst containing the improved carrier, as well as an improved process for the epoxidation of ethylene using the catalyst of the invention.

What is claimed is: 
     
       1. An ethylene epoxidation catalyst comprising:
 a) a carrier comprising alumina in combination with a stability-enhancing amount of mullite, wherein the carrier possesses a multimodal pore size distribution; 
 b) a catalytic amount of silver deposited on and/or in said carrier; and 
 c) a promoting amount of rhenium deposited on and/or in said carrier. 
 
     
     
       2. The catalyst according to  claim 1 , wherein the alumina is a-alumina. 
     
     
       3. The catalyst according to  claim 1 , wherein the stability-enhancing amount of mullite is about 0.5-20% mullite. 
     
     
       4. The catalyst according to  claim 1 , wherein the stability-enhancing amount of mullite is about 1-15% mullite. 
     
     
       5. The catalyst according to  claim 1 , wherein the stability-enhancing amount of mullite is about 1-12% mullite. 
     
     
       6. The catalyst according to  claim 1 , wherein the stability-enhancing amount of mullite is about 3-15% mullite. 
     
     
       7. The catalyst according to  claim 1 , wherein the stability-enhancing amount of mullite is about 3-12% mullite. 
     
     
       8. The catalyst according to  claim 1 , further comprising a promoting amount of an alkali or alkaline earth metal. 
     
     
       9. The catalyst according to  claim 1 , further comprising a promoting amount of cesium. 
     
     
       10. The catalyst according to  claim 1 , further comprising a promoting amount of tungsten. 
     
     
       11. The catalyst according to  claim 1 , further comprising a promoting amount of sulfur. 
     
     
       12. The catalyst according to  claim 1 , further comprising a promoting amount of cesium, lithium, tungsten, and sulfur. 
     
     
       13. The catalyst according to  claim 1 , further comprising a promoting amount of cesium, lithium, and sulfur. 
     
     
       14. The catalyst according to  claim 1 , wherein the carrier possesses pores having diameters of at least about 0.01 μm and up to about 5 μm. 
     
     
       15. The catalyst according to  claim 1 , wherein the carrier possesses a bimodal distribution of pore sizes comprising a first and a second distribution of pore sizes, wherein each distribution of pore sizes possesses a different mean pore size. 
     
     
       16. The catalyst according to  claim 15 , wherein at least one distribution of pore sizes possesses a mean pore size within the range 0.01-5 μm. 
     
     
       17. The catalyst according to  claim 15 , wherein the first and second distribution of pore sizes each possesses a mean pore size within the range 0.01-5 μm.